A frequent problem encountered by resists used to process supports comprising semiconductor devices is reflectivity back into the resist of the activating radiation by the substrate, especially those containing highly reflective topographies. Such reflectivity tends to cause standing wave ripples and reflective notches, which degrade the resolution of the photoresist. Degradation of the microimagery in the processed resist is particularly bad when the support is non-planar and/or highly reflective. One approach to this problem is to incorporate an anti-reflective dye either in the photoresist layer or an adjacent layer.
Although there are many anti-reflective dyes known in the silver halide photography art, there are conditions peculiar to the photoresist art which render many such dyes unsuitable for use in photoresist elements. One of these is the high temperature baking that is given to the resist, prior to exposure. For example, it is common to force the resist layer, the anti-reflective layer, or the planarizing layer into a more planar configuration by baking it until it melts and flows, creating a condition known as "planarization." Such baking can require temperatures as high as 200.degree. C. or more. High temperatures are deleterious unless great care is taken to select dyes which are non-volatile and thermally stable. Furthermore, dyes which might be expected to be non-volatile and thermally stable, such as very high molecular weight dyes, generally do not exhibit good solubility in solvents, such as chlorobenzene and ethoxyethyl acetate, which are commonly employed in processing semiconductor devices.
A problem with prior art anti-reflective dyes, known to be useful in anti-reflective coatings for use with photoresists, such as Sudan Orange G, described in Proceedings of the Microelectronics Seminar, 1980, pp. 109-113, is that such dyes are not resistant to volatilization when heated to temperatures of as high as 200.degree. C. or more for 30 min., which is desirable for planarization.